<select id ="user_id" onchange="new Ajax.Updater('<%= "b_" + @req.id.to_s %>', '<%= "/requirements/" + @req.id.to_s + "/change_developer_finish" %>', {method:'put', parameters: {user_id:this.value}})" name="requirement[user_id]">
  <option value=""></option>
  <% for user in @users %>
  <option value="<%= user.id %>"><%= user.name %></option>
  <% end %>
</select>